1. Field of the Invention
The present invention relates to an image analysis device and an image analysis method that detect a polyp from a medical image.
2. Description of the Related Art
In the medical field, a diagnosis has been widely performed using an image pickup instrument such as X-ray, CT, MRI, ultrasound observation device, and endoscopic device.
For example, in an endoscopic device, the diagnosis can be performed by inserting an elongated insertion section in a body cavity and using image pickup section such as a solid-state image pickup device to thereby observe intracavital organs on a monitor screen. An ultrasound endoscopic device is also widely used that is capable of detecting or diagnosing by irradiating ultrasound to the intracavital organs and observing the conditions of the intracavital organs on a monitor screen based on the reflection or the transmittance of the ultrasound.
The conclusive diagnosis using images picked up by these devices is largely dependent on the subjectivity of the doctor. Thus, there is a diagnosis supporting device that supports the doctor's diagnosis by calculating a feature value related to an image to be picked up using an image analysis method and presenting objective and numerical diagnosis supporting information to the doctor.
The feature value herein denotes a numerical value that reflects various findings on the image and can be obtained by applying the image analysis method.
For example, in an endoscopic image, a finding related to the color tone such as redness of mucous surface, a finding related to the shape of blood vessels such as bending and meandering of blood vessels observed in a transparent blood vessel image, and a finding related to the mucous pattern in the gastric area are important factors in malignancy diagnosis of lesion. Non-Patent Document 1 (“Digestive Endoscopy”, 2001 Vol. 13 No. 3 vol. 13, Tokyo Igakusha P349-354) is an example of discrimination of lesion malignancy based on a mucous finding and a finding related to the shape of blood vessels.
For example, in Japanese Patent Application Laid-Open Publication No. 2005-157902 and other documents, an image analysis method is disclosed that is capable of improving the lesion determination accuracy based on an objectified result of the findings using the feature value. In Japanese Patent Application Laid-Open Publication No. 2005-157902, blood vessels in the digestive tract image are extracted as a linear pattern for use in the lesion determination in the image analysis method.